Field of Invention
This invention relates to a method for manufacturing a combination type thin film magnetic head having a writing inductive type thin film magnetic conversion element and a reading magnetoresistive effective type thin film magnetic conversion element which are, insulated magnetically and electrically, stacked on a substrate. Thin invention also relates to a wafer to be used in manufacturing the same thin film magnetic head.
Recently, with the development of surface recording densities in hard disk devices, thin film magnetic heads are required to have excellent characteristics. For developing the performances of the reading thin film magnetic heads, magnetoresistive effective type thin film magnetic conversion elements are widely available. Although the magnetoresistive effective type thin film magnetic conversion elements using a normal anisotropic magnetoresistive (AMR) effect has been generally employed, the ones using a giant magnetoresistive (GMR), each element having a several times as large resistance variation as the AMR element, have been developed. In this specification, each of these AMR elements and GMR elements, etc., is generically called as a xe2x80x9cmagnetoresistive effective type thin film magnetic headxe2x80x9d (often abbreviated to an xe2x80x9cMR elementxe2x80x9d hereinafter) in brief.
The use of the AMR element enables a surface recording density of several giga bits/inch2 to be realized, and the use of the GMR element enables the surface recording density to be more enhanced. Such a high surface recording density can realize a hard disk drive having a large capacity of more than 10 G bites. The height of the MR element (often called as an xe2x80x9cMR Heightxe2x80x9d hereinafter) is a factor to determine the performance of the reading thin film magnetic head. The MR height is the distance of the MR element from an air bearing surface (often called as an xe2x80x9cABSxe2x80x9d hereinafter) to its edge, and in a practical manufacturing process of the thin film magnetic head, the desired MR height can be obtained by controlling the polishing amount of the end of the head in forming the ABS.
In addition, the performances of the writing thin film magnetic heads are required to be developed. The development of the surface recording density requires an enhancement of a track density in a magnetic recording medium. Thus, the width of the write gap in the air bearing surface has to be narrowed to a submicron order from a several micron order, and for realizing it, a semiconductor processing technique is employed. A throat height (often called as a xe2x80x9cTHxe2x80x9d hereinafter) is a factor to determine the performance of the writing thin film magnetic head. The throat height is the distance of the magnetic pole portion to the ABS from the edge of the insulating film to electrically separate the thin film coil, and is desired to be as short as possible.
FIGS. 1-12 shows successive manufacturing steps of a conventionally normal thin film magnetic head and the same magnetic head. The thin film magnetic head is a combination type thin film magnetic head which has a writing inductive type thin film magnetic head and a reading thin film magnetic head with the MR element.
First of all, as shown in FIG. 1, an insulating layer 112 made of alumina (Al2O3) is formed in a thickness of about 5-10 xcexcm on a substrate 111 made of alumina-titanium-carbon (AlTiC), for example. Then, as shown in FIG. 2, a bottom shield gap layer 113 is formed for protecting the reading MR reproducing element against an external magnetic field, and thereafter, as shown in FIG. 3, an insulating layer 114 is formed, of alumina, in a thickness of 100-150 nm by sputtering.
Subsequently, as shown in FIG. 3, a magnetoresistive layer 115 to constitute the MR reproducing element is formed, of a material having a magnetoresistive effect, in a thickness of several ten nm on the insulating layer 114, and thereafter, is processed in a desired formation through mask-alignment. Next, as shown in FIG. 4, an insulating layer 116 similar to the insulating film 114 is formed, and as shown in FIG. 5, a magnetic layer 117 is formed, of permalloy, in a thickness of 3-4 xcexcm on the insulating layer 116. The magnetic layer 117 serves as a top shield magnetic layer to magnetically shield the MR reproducing element with the bottom shield magnetic layer 113, and also as a bottom magnetic layer for the writing thin film magnetic head. Herein, for convenience, the magnetic layer 117 is called as a xe2x80x9cfirst magnetic layerxe2x80x9d because it serves as one magnetic layer in the writing magnetic head.
Subsequently, a gap layer 118 is formed, of a non-magnetic material, e.g., alumina, in a thickness of 150-300 nm, on the first magnetic layer 117. Then, on the gap layer is formed, in a desired pattern through precise mask-alignment, an insulative photoresist 119, on which a first layer-thin film coil 120 is formed, of Cu, for example, on the photoresist.
Next, as shown in FIG. 7, an insulative photoresist layer 121 is formed on the first layer-thin film coil 120 through precise mask-alignment, and thereafter, is baked at a temperature of 250xc2x0 C., for example to flatten its top surface. Moreover, as shown in FIG. 8, a second layer-thin film coil 122 is formed on the flattened top surface of the photoresist layer 121, and a photoresist layer 123 is formed on the second layer-thin film coil 122 through precise mask-alignment. Thereafter, the photoresist 123 is baked at a temperature of 250xc2x0 C., for example, to flatten its top surface. As mentioned above, the photoresist layers 119, 121, 123 are formed through the precise mask-alignment because the edges of the photoresist are the standard positions to define the Throat Height (TH) and the MR Height.
Subsequently, a second magnetic layer 124 is selectively formed, of permalloy, for example, on the gap layer 118 and the photoresist layers 119, 121, 123 alongside a given pattern. The second magnetic layer 124 is contacted with the first magnetic layer 117 in the remote side from the magnetoresistive layer 115, and the thin film coils 120 and 122 pass through the close magnetic circuit composed of the first and the second magnetic layers 117 and 124. The second magnetic layer 124 has the magnetic pole portion having a given shape and a given size to define a track width. Moreover, an overcoat layer 125 is formed, of alumina, on the exposed surfaces of the second magnetic layer 124 and the gap layer 118. Practically, a conductive pattern including the leads and pods to electrically connect the thin film coils 120, 122 and the MR reproducing element is formed, but not shown in the figures.
In the practical manufacture of the combination type thin film magnetic head, the above substrate 111 is composed of a wafer. Then, many thin film magnetic head units are formed on the wafer, arranged in matrix thereon, and the wafer is cut out in plural bars, each bar having the thin film magnetic head units in a row. The ends of the bar are polished to form the air bearing surfaces of the plural thin film magnetic heads at the same time, and then, the bar is cut out to obtain the combination type thin film magnetic head, respectively. That is, by polishing the side surface 126 in the side of the magnetoresistive layer 115 of the assembly shown in FIG. 10, an air bearing surface 127 is formed, opposing to a magnetic recording medium. During the formation of the air bearing surface, the magnetoresistive layer 115 is polished to obtain the MR reproducing element 128, and at the same time, the Throat Height TH and the MR Height are defined.
Because in the polish of the air bearing surface, the polish of the Throat Height and the MR Height can not monitored, the change of the resistance of the magnetoresistive layer 115 with the decrease of its height is monitored as the change of the current, for example by a resistance-measuring circuit connected to a conductive pattern (not shown in the figures) connected to the magnetoresistive layer 115 and the polished amount of magnetoresistive layer 115 is calculated from the current change. That is, by polishing the side surface 126 so that the MR reproducing element 128 can have a given resistance, the desired MR Height and the Throat Height can be obtained.
FIGS. 10, 11 and 12 are cross sectional view, an front view and a plan view of the conventional combination type thin film magnetic head manufactured by the above process, respectively. In FIG. 10, the alumina insulating layers 114 and 116 surrounding the MR reproducing element are depicted as a single insulating layer, respectively, and for simplifying the figures, the thin film coils 120 and 122 are depicted in concentric circle. As is shown in FIG. 10 clearly, the Apex Angle, which is defined as an angle xcex8 between the line segment S linking the corners of the side surfaces of the photoresist layers 119, 121 and 123 to separate the thin film coils 120 and 122 in insulation and the top surface of the second magnetic layer 124, is an important factor to determine the performances of the thin film magnetic head, in addition to the above Throat Height and the MR height. Moreover, as is shown in the plan view of FIG. 12, the magnetic pole portion 124a of the second magnetic layer 124 has a narrowed width W, which defines the track width in the recording magnetic medium, so for realizing the high surface recording density, it is desired to narrow the width W as short as possible.
Since the development of the surface recording density of the magnetic recording density requires the enhancement of a recording head and a reproducing head, the above combination type thin film magnetic head requires a submicron-order control using a semiconductor-processing technique in its manufacturing process. It is the Throat Height of the writing inductive type thin film magnetic head and the MR Height of the reading thin film magnetic head composed of the MR reproducing element that largely influence the process yield of the combination type thin film magnetic head.
As is explained with reference to FIGS. 1-12, in the conventional manufacturing method of a thin film magnetic head, the resistance of the magnetoresistive layer 115 in the MR reproducing element is measured and then, the desired MR Height and Throat Height can be obtained through controlling the polished amount corresponding to the resistance. However, the relation between the resistance of the magnetoresistive layer 115 and the MR Height is not constant, so that the conventional method almost never give the desired MR Height. That is, since the magnetoresistive layer 115 has the fluctuation of its resistance due to its composition and its manufacturing conditions, the desired resistance does not always give the desired MR Height. The deviation of the MR Height from its desired value results in the deviation of the Throat Height. In this way, even if the resistance of the MR reproducing element has its desired value, the MR Height and the Throat Height often deviates from their desired values, resulting in the deterioration of the combination type thin film magnetic head.
To iron out the problem, for example, the specification of U.S. Pat. No. 4,689,877 (Kokai publication Kokai Sho 63-29315:JP A 63-29315) discloses that plural switching contacts, which are successively opened with the procedure of the polishing of the bar, are formed in series on the sides of the bar on which plural thin film magnetic heads are formed and guiding resistances, in which the resistance values varies continuously with the procedure of the polishing, are formed in parallel to each of the switching contacts, and the open of the switching contacts is detected through measuring the change of all the guiding resistances connected in series one another to give a desired Throat Height.
However, the conventional manufacturing method requires the additional manufacturing steps of forming the plural switching contacts on the both sides of the bar and forming the plural guiding resistances, resulting in the large degradation of the throughput. That is, the method requires the additional steps of forming the switching contacts of a conductive pattern and forming the guiding resistances of a resistive material. Moreover, the plural switching contacts are formed so that the distance between the neighboring switching contacts can be much larger than the size of the element constituting each switching contact in the polishing direction. Thus, the detection of the step-by-step change of the Throat Height from the measurement of the cut-off of the switching contacts and the detection of the continuous change of the Throat Height between the successive step-by-step change control the Throat Height, but the change of the guiding resistances fluctuates, so that they have difficulty in the precise minute control of the Throat Height, for example, 0.1-0.3 xcexcm order-control of the Throat Height.
Moreover, the specification of U.S. Pat. No. 5,065,483 (Kokai publication Kokai Hei 4-360008: JP A 4-360008) discloses that as mentioned above, a polished amount of an air bearing surface is detected by using a resistive lapping element to detect the polished amount from its resistance change and a perfect lapping element to be polished perfectly, which are made of the same material as that of a magnetoresistive element. In this case, the step of forming the elements to detect the polished amount is simplified, but the resistance of the magnetoresistive material fluctuates relatively large, so that it is difficult to detect the polished amount from the change of the resistance precisely.
2. Description of Related Art
It is an object of the present invention to provide a method for manufacturing a combination type thin film magnetic head able to control the Throat Height and the MR Height of the same magnetic head precisely under their desired values without the decrease of their throughput.
It is another object of the present invention to provide a wafer suitable for the manufacturing method of a combination type thin film magnetic head.
A method for manufacturing a combination type thin film magnetic head comprises the steps of:
forming a first electrode member for a polished amount-monitoring element of the same magnetic material as that of a first magnetic pole portion constituting an inductive type thin film magnetic head so that the first electrode member can have the almost same construction as that of the first magnetic pole portion at the same time of the formation of a first magnetic member having the first magnetic pole portion before or after forming the reading magnetoresistive effective type thin film magnetic conversion element on the wafer constituting the substrate,
forming a write gap layer so as to cover the first magnetic pole portion of the first magnetic member constituting an inductive type thin film magnetic head,
forming a thin film coil supported by an insulating layer on the first magnetic member and the first electrode member,
forming a second electrode member for the polished amount-monitoring element of the same magnetic material as that of a second magnetic pole portion opposing to the first magnetic pole portion via the write gap layer and constituting a second magnetic member of the inductive type thin film magnetic head which has the second magnetic pole portion and is magnetically connected to the first magnetic member so that the second electrode member can have the almost same construction as that of the second magnetic pole portion, directly contacted with the first electrode member without the write gap layer and the inside edge opposite to an air bearing surface of the joined surface between the first and second electrode members can have a given position to the standard position of the Throat Height zero, at the same time of the formation of the second magnetic member,
forming a first and a second lead members connected to the first and the second electrode member for the polished amount-monitoring element respectively,
cutting the wafer in plural bars so that each bar can have plural combination type thin film magnetic head units and at least one polished amount-monitoring element after forming the writing thin film magnetic conversion element and the reading thin film magnetic conversion element on the wafer,
polishing the ends of the bars with monitoring the polished amount of the air bearing surface of the thin film magnetic head by electrically detecting the continuation and discontinuation between the first and second electrode member of the polished amount-monitoring element with a measuring circuit connected to the first and second lead members, and
cutting the bar in plural combination type thin film magnetic head, each head having the air bearing surface polished so as to obtain a desired Throat Height.
According to the method for manufacturing a combination type thin film magnetic head of the present invention, since the first and second electrode member of the polished amount-monitoring element are made of the same material as the material constituting the inductive type thin film magnetic head, the polished amount-monitoring element does not need a peculiar material or process in its manufacture, so that the manufacturing method can be carried out easily and not expensively with its large throughput. Moreover, since the polished amount is measured by detecting the continuation or the discontinuation between the first and the second electrode members, the polished amount can be detected precisely without the influence of the resistance change in the magnetic resistive material as mentioned above.
In the manufacturing method of a combination type thin film magnetic head of the present invention, it is desired that each bar has plural polished amount-monitoring element, each having the same distance or the different distance to the standard position of the Throat Height zero from the inside edge opposite to the air bearing surface of the joined surface between the first and second electrode member. In the case that each polished amount-monitoring element has different distance to the standard position of the Throat Height zero from the inside edge opposite to the air bearing surface of the joined surface between the first and second electrode members, it has preferably the different distance by the 0.1-0.5 xcexcm. Thereby, while the Throat Height of the thin film magnetic head, which is several micron to several submicron order, extremely short, is controlled precisely, the air bearing surface can be polished in submicron order.
Moreover, in the manufacturing method according to the present invention, it is desired that the plural polished amount-monitoring elements are dispersedly formed in the plural combination type thin film magnetic head units formed on the bar. In this case, the error of the Throat Height due to the inclination of the side of the air bearing surface can be reduced during the polish of the air bearing surface, so that the Throat Height can be controlled more precisely.
This invention also relates to a wafer to be used in the above manufacturing method. Concretely, this invention also relates to a wafer to be used in manufacturing a combination type thin film magnetic head in which a writing inductive type thin film magnetic conversion element and a reading magnetoresistive effective type thin film magnetic conversion element are stacked on a surface of a substrate with magnetically and electrically insulated, wherein in each area which is cut out later to constitute a bar,
plural inductive type thin film magnetic heads, each having a first magnetic member with a first magnetic pole portion, a write gap layer formed so as to cover the first magnetic pole portion, a thin film coil formed on the first magnetic member so as to be supported by an insulating layer and a second magnetic member with a second magnetic pole portion opposing to the first magnetic pole portion via the write gap layer, magnetically connected to the first magnetic member in the opposite position to the first and second magnetic pole portions, and
at least one polished amount-monitoring element having a first electrode member made of the same magnetic material as the first magnetic pole portion and having the almost same construction as that of first magnetic pole portion at the same time of the formation thereof, a thin film coil formed on the first electrode member so as to be supported by an insulating layer, a second electrode member having the same construction as that of the second magnetic pole portion, made of the same magnetic material as that of the second magnetic pole portion and formed so that it can directly contact with the first electrode member via the write gap layer and the inside edge of the opposite to an air bearing surface of its joined surface for the first electrode member can have a given position for the standard position of the Throat Height zero, and a first and a second lead members connected to the first and the second electrode members respectively,
are formed with plural combination type thin film magnetic head units.
In a preferred embodiment of the wafer of the present invention, plural polished amount-monitoring elements, each having the same distance or the different distance to the standard position of the Throat Height zero from the inside edge opposite to the air bearing surface of the joined surface between the first and second electrode members, are formed in the area for the bar to be formed. In the case that each polished amount-monitoring element has the same distance to the standard position of the Throat Height zero from the inside edge opposite to the air bearing surface of the joined surface between the first and second electrode members, it is desired to form the plural polished amount-monitoring elements in the both ends of the bar or dispersedly. Moreover, in the case that each polished amount-monitoring elements has the different distance to the standard position of the Throat Height zero from the inside edge opposite to the air bearing surface of the joined surface between the first and second electrode members, it is desired to form the plural polished amount-monitoring elements so that the distance may be different by the 0.1-0.5 xcexcm. Since in the above conventional method of detecting the polished amount by measuring the resistance change with the procedure of the polish, the resistance fluctuates largely, so that it is very difficult to detect the polished amount precisely.
Moreover, in the case that the plural polished amount-monitoring elements are formed in each area to be bar, as mentioned above, it is desired to form the monitoring elements dispersedly in the plural combination type thin film magnetic head units. Thereby, the influence of the inclination of the bar during the polish of the air bearing surface can be reduced.